Chapter 49. GiST Indexes

GiST stands
for Generalized Search Tree. It is a balanced, tree-structured
access method, that acts as a base template in which to
implement arbitrary indexing schemes. B+-trees, R-trees and
many other indexing schemes can be implemented in
GiST.

One advantage of GiST is
that it allows the development of custom data types with the
appropriate access methods, by an expert in the domain of the
data type, rather than a database expert.